Problem using byte indexed pixel format in setPixels method of PixelWriter

Question

I try to construct a byte array and set it to a WritableImage using PixelWriter's setPixels method.
If I use an RGB pixel format, it works. If I use a byte-indexed pixel format, I get an NPE.
The stride etc should be fine if I'm not mistaken.
java.lang.NullPointerException
     at com.sun.javafx.image.impl.BaseByteToByteConverter.<init>(BaseByteToByteConverter.java:45)
     at com.sun.javafx.image.impl.General$ByteToByteGeneralConverter.<init>(General.java:69)
     at com.sun.javafx.image.impl.General.create(General.java:44)
     at com.sun.javafx.image.PixelUtils.getB2BConverter(PixelUtils.java:223)
     at com.sun.prism.Image$ByteAccess.setPixels(Image.java:770)
     at com.sun.prism.Image.setPixels(Image.java:606)
     at javafx.scene.image.WritableImage$2.setPixels(WritableImage.java:199)
Short, self-contained example here:
import java.nio.ByteBuffer;
import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.image.ImageView;
import javafx.scene.image.PixelFormat;
import javafx.scene.image.WritableImage;
import javafx.scene.layout.BorderPane;
import javafx.stage.Stage;
public class IndexedColorTestApp extends Application {
    public static void main(String[] args) {
        launch(args);
    @Override
    public void start(Stage primaryStage) {
        BorderPane borderPane = new BorderPane();
        Scene scene = new Scene(borderPane, 600, 1100);
        primaryStage.setScene(scene);
        ImageView imageView = new ImageView();
        borderPane.setCenter(imageView);
        primaryStage.show();
        int imageWidth = 200;
        int imageHeight = 200;
        WritableImage writableImage = new WritableImage(imageWidth, imageHeight);
        // this works
        byte[] rgbBytePixels = new byte[imageWidth * imageHeight * 3];
        PixelFormat<ByteBuffer> byteRgbFormat = PixelFormat.getByteRgbInstance();
        writableImage.getPixelWriter().setPixels(0, 0, imageWidth, imageHeight,
                                                 byteRgbFormat, rgbBytePixels, 0, imageWidth * 3);
        imageView.setImage(writableImage);
        // this throws an NPE in setPixels()
        byte[] indexedBytePixels = new byte[imageWidth * imageHeight];
        int[] colorPalette = new int[256];
        PixelFormat<ByteBuffer> byteIndexedFormat = PixelFormat.createByteIndexedInstance(colorPalette);
        writableImage.getPixelWriter().setPixels(0, 0, imageWidth, imageHeight,
                                                 byteIndexedFormat, indexedBytePixels, 0, imageWidth);
        imageView.setImage(writableImage);
}If there's no solution, maybe someone knows a workaround? We chose to use indexed format because of data size / performance reasons.
Edited by: Andipa on 01.03.2013 10:52

Answer 1

You have found a platform bug, file it against the Runtime project at => http://javafx-jira.kenai.com with your sample code and a link back to this forum question.
Byte indexed pixel formats seem like a feature which was never completely (or perhaps even hardly at all) implemented to me.
The PixelFormat type your failed case is using is (PixelFormat.Type.BYTE_INDEXED):
PixelFormat<ByteBuffer> byteIndexedFormat = PixelFormat.createByteIndexedInstance(colorPalette);
System.out.println(byteIndexedFormat.getType());These are the valid PixelFormat types =>
http://docs.oracle.com/javafx/2/api/javafx/scene/image/PixelFormat.Type.html
BYTE_BGRA
The pixels are stored in adjacent bytes with the non-premultiplied components stored in order of increasing index: blue, green, red, alpha.
BYTE_BGRA_PRE
The pixels are stored in adjacent bytes with the premultiplied components stored in order of increasing index: blue, green, red, alpha.
BYTE_INDEXED
The pixel colors are referenced by byte indices stored in the pixel array, with the byte interpreted as an unsigned index into a list of colors provided by the PixelFormat object.
BYTE_RGB
The opaque pixels are stored in adjacent bytes with the color components stored in order of increasing index: red, green, blue.
INT_ARGB
The pixels are stored in 32-bit integers with the non-premultiplied components stored in order, from MSb to LSb: alpha, red, green, blue.
INT_ARGB_PRE
The pixels are stored in 32-bit integers with the premultiplied components stored in order, from MSb to LSb: alpha, red, green, blue.As the native pixel format for a WritableImage is not the same as the pixel format you are using, the JavaFX platform needs to do a conversion by reading the pixels in one format and writing them in another format. To do this it must be able to determine a PixelGetter for your PixelFormat (the PixelGetter is an internal thing, not public API).
And here is the source the determines the PixelGetter for a given PixelFormat type:
http://hg.openjdk.java.net/openjfx/8/master/rt/file/06afa65a1aa3/javafx-ui-common/src/com/sun/javafx/image/PixelUtils.java
119     public static <T extends Buffer> PixelGetter<T> getGetter(PixelFormat<T> pf) {
120         switch (pf.getType()) {
121             case BYTE_BGRA:
122                 return (PixelGetter<T>) ByteBgra.getter;
123             case BYTE_BGRA_PRE:
124                 return (PixelGetter<T>) ByteBgraPre.getter;
125             case INT_ARGB:
126                 return (PixelGetter<T>) IntArgb.getter;
127             case INT_ARGB_PRE:
128                 return (PixelGetter<T>) IntArgbPre.getter;
129             case BYTE_RGB:
130                 return (PixelGetter<T>) ByteRgb.getter;
131         }
132         return null;
133     }As you can see, the BYTE_INDEXED format is not handled and null is returned instead . . . this is the source of your NullPointerException.